Since Barack Obama’s election, the debate about his presidency has largely centered on his ambitious domestic agenda. The stimulus boondoggle that expanded the debt but did nothing to help the economy and the vast expansion of entitlements that were part of Obama’s healthcare plan helped galvanize the Republican opposition to the president and paved the way for the GOP’s massive midterm election win last November. Fiscal issues have continued to dominate the discussion since then, but the killing of Osama bin Laden has altered the focus of American politics, at least for the moment. That should be a signal for the Republican presidential field to devote at least some attention to the primary job of any president: foreign policy and security issues.

It’s not as if nobody in the GOP has been talking about foreign policy. Mitt Romney and Tim Pawlenty have been sharply critical of Obama’s heretofore-apologetic demeanor towards the world. Radical libertarian Ron Paul is an unrepentant isolationist. That’s a foreign policy of a sort, albeit an irrational one. Former United Nations ambassador John Bolton may be running more for the post of secretary of state in a future Republican administration than president, but his largely symbolic candidacy has been all about the need to address the threats we face from abroad.

But with the first Republican presidential debate scheduled for this Thursday in South Carolina on Thursday, security issues are probably moving up on the priority list for the candidates. The race can probably be broken down at this stage into two separate battles.

There is one battle in which the more establishment-oriented candidates who try to speak as if they could actually be a president are competing against each other. And there is another battle to determine the most viable populist. With Romney opting out of the South Carolina debate (and who can blame him since nothing that happens this early can be termed decisive), Pawlenty has a chance to step to the fore in the first category. It will be interesting to see if the former Minnesota governor who espouses an assertive role in the world for the United States will directly challenge Paul. With bin Laden on everyone’s mind and the need for any presidential challenger to address the fact that he will be running for the post of commander-in-chief and not accountant-in-chief, Pawlenty as well as the others could seize this early opportunity to stake out a position of credibility on foreign affairs.

Unlike 9/11 and the subsequent wars in Iraq and Afghanistan, bin Laden’s death doesn’t transform the next election the way the 2004 race was altered. Just as the fate of the economy will ultimately determine Obama’s chances of reelection, there is little doubt that stances on fiscal issues will be determinative in the GOP primary.

The only candidate from either party with serious security or foreign policy experience to be elected president in the last 40 years was George H.W. Bush so the current contenders shouldn’t despair. But this week has been a wake-up call for Republicans. If they thought they could cruise through the next election cycle by focusing solely on the budget, they were mistaken. Like it or not, they are going to have to nominate someone whom the country can at least imagine as being capable of ordering American troops into action as Obama has just done.